Alert archive / Michigan / Mesoscale Discussions in 2012

Mesoscale Discussion 1655

July 30, 201214 counties in Michigan; 12 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Jul 30, 2012, 7:16 PM EDT for 14 counties in Michigan; 12 counties in Wisconsin. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: Jul 30, 2012, 7:16 PM EDT (23:16 UTC)
Expired: Jul 30, 2012, 8:15 PM EDT
In force: 59 min
Issued by: the Storm Prediction Center

All 26 counties

Antrim County, MI, Benzie County, MI, Charlevoix County, MI, Delta County, MI, Emmet County, MI, Grand Traverse County, MI, Lake County, MI, Leelanau County, MI, Mackinac County, MI, Manistee County, MI, Mason County, MI, Menominee County, MI, Schoolcraft County, MI, Wexford County, MI, Brown County, WI, Calumet County, WI, Door County, WI, Kewaunee County, WI, Manitowoc County, WI, Marinette County, WI, Menominee County, WI, Oconto County, WI, Outagamie County, WI, Portage County, WI, Shawano County, WI, Waupaca County, WI

The radar

The Green Bay radar (KGRB), 89 km from the middle of the area, began a volume at 23:18 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 11.3 hours before the alert went out and 89 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 455 J/kg
Mixed-layer CIN: -119 J/kg
Mixed-layer LCL: 805 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 132 m²/s²
0-3 km storm-relative helicity: 114 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

620 
ACUS11 KWNS 302316
SWOMCD
SPC MCD 302316 
MIZ000-WIZ000-310015-

MESOSCALE DISCUSSION 1655
NWS STORM PREDICTION CENTER NORMAN OK
0616 PM CDT MON JUL 30 2012

AREAS AFFECTED...NERN WI...CNTRL AND ERN UPPER MI AND NWRN LOWER MI

CONCERNING...SEVERE THUNDERSTORM WATCH 540...

VALID 302316Z - 310015Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 540
CONTINUES.

SUMMARY...THE THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL WILL
PERSIST NEXT HOUR OR SO FROM EXTREME NERN WI INTO THE CNTRL AND ERN
UPPER PENINSULA OF MI. ACTIVITY WILL SOON BEGIN TO CROSS LAKE MI.
UNLESS THE STORMS MAINTAIN ORGANIZATION AND INTENSITY...A WW WILL
PROBABLY NOT BE NEEDED FOR LOWER MI.

DISCUSSION...STORMS CONTINUE ALONG AND JUST AHEAD OF A COLD FRONT
FROM EXTREME NERN WI INTO THE ERN PENINSULA OF UPPER MI AND IS
APPROACHING THE NWRN SHORE OF LAKE MI. INSTABILITY IS LIMITED
FARTHER DOWNSTREAM OVER THE NRN PART OF LOWER MI WHERE DEWPOINTS ARE
ONLY IN THE LOWER 60S AND TEMPERATURES IN THE LOW 80S. THE SFC LAYER
WILL CONTINUE TO STABILIZE WITH ONSET OF NOCTURNAL COOLING.
HOWEVER...MODEST 850 MB MOISTURE ADVECTION MAY CONTRIBUTE TO SOME
DESTABILIZATION ABOVE THE SFC. CURRENT THINKING IS THAT STORMS WILL
POSE A SEVERE THREAT FROM ERN WI INTO ERN LOWER MI THROUGH AT LEAST
00Z...BUT WILL BEGIN TO WEAKEN AS THEY CROSS THE LAKE.

..DIAL.. 07/30/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...APX...GRR...MQT...GRB...ARX...

LAT...LON   44288990 46488628 46078422 44578521 43938584 44018817
            44288990

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 30, 1:26 PM EDT	Mesoscale Discussion	SPC	Alger, Baraga, Benzie, Charlevoix, Delta, Dickinson and 7 more	64 min
Jul 30, 2:28 PM EDT	Severe Thunderstorm Watch	SPC	Alger, Delta, Dickinson, Iron, Luce, Marquette and 2 more	8 hr
Jul 30, 4:49 PM EDT	Mesoscale Discussion	SPC	Alger, Delta, Dickinson, Iron, Marquette, Menominee and 1 more	56 min

Nearby

Mesoscale Discussions in Michigan, 2012 Mesoscale Discussions in Wisconsin, 2012 Every mesoscale discussion in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.